In a gas turbine aeronautic engine, the fan retention housing fulfils several functions. It is formed by a relatively thin metallic wall defining the air inlet in the engine, supports abradable material opposite the tips of the fan blades as well as any absorption structure of sound waves for the acoustic input treatment of the engine, and incorporates or supports a retention shield, at the level of the fan.
Documents EP 1 674 671 and EP 1 961 923 have proposed producing a fan retention housing of composite material, comprising for example a fibrous reinforcement densified by a matrix. The fibrous reinforcement can be formed by a winding in layers superposed on a mandrel of a fibrous texture obtained by three-dimensional weaving with evolutive thickness, to integrate the retention shield by simple localised increase in thickness.
These housings made of composite materials have many advantages, including especially their weight reduced in comparison to equivalent metallic housings. Yet, since the matrix of these composite materials generally comprises material polymer such as resin, they exhibit major electrical resistance and therefore do not adequately conduct electricity to correctly evacuate electric power. However, the electrical equipment of the housing can be subject to an aggressive electromagnetic environment (especially to high-intensity radiated fields (or HIRF), lightning strikes, electro-magnetic interference (EMI), etc., in which they must be capable of functioning nominally.
The result is considerable risk of damaging the electrical equipment of the engine, including some computers essential to proper operation of the engine.
Also, when electrical energy cannot be evacuated, it causes a substantial rise in temperature of the housing by joule effect. Composite materials used to make the fan retention housings are limited to a use temperature of generally under a hundred degrees. If this temperature is exceeded, the housing risks melting at least locally or burning (combustion) and no longer being able to support all or some of the electrical equipment which they support.
Document U.S. 2013/189868 has proposed a rigid structure in which several electrical conductors are embedded, to reduce the bulk and weight of the conventional harness and simplify their handling. This document however provides no technical solution for easily evacuating loads and intensities which might be circulating in a housing made of electrically insulating material.
Document U.S. Pat. No. 5,174,110 as such describes the fact that an aeronautic engine includes electric cables for making electrical connections in an aeronautic engine. But, neither does the basic idea of this document improve evacuation of loads and intensities in such a housing.